Handling video files better

[justinchen]

A couple suggestions for handling video files more appropriately.

1. Store duration attribute in DB

2. Pass resource_type when making API calls (otherwise it errors with resource not found).

module Attachinary
    def destroy_file
    	Cloudinary::Uploader.destroy(public_id, {resource_type: resource_type}) if public_id && !keep_remote?
    end
  end
end